From: Jens Axboe <axboe@suse.de>,
      Chris Mason,
      me, others.

The global unplug list causes horrid spinlock contention on many-disk
many-CPU setups - throughput is worse than halved.

The other problem with the global unplugging is of course that it will cause
the unplugging of queues which are unrelated to the I/O upon which the caller
is about to wait.

So what we do to solve these problems is to remove the global unplug and set
up the infrastructure under which the VFS can tell the block layer to unplug
only those queues which are relevant to the page or buffer_head whcih is
about to be waited upon.

We do this via the very appropriate address_space->backing_dev_info structure.

Most of the complexity is in devicemapper, MD and swapper_space, because for
these backing devices, multiple queues may need to be unplugged to complete a
page/buffer I/O.  In each case we ensure that data structures are in place to
permit us to identify all the lower-level queues which contribute to the
higher-level backing_dev_info.  Each contributing queue is told to unplug in
response to a higher-level unplug.

To simplify things in various places we also introduce the concept of a
"synchronous BIO": it is tagged with BIO_RW_SYNC.  The block layer will
perform an immediate unplug when it sees one of these go past.

From: Joe Thornber <thornber@redhat.com>

dm.c: remove __dm_request (merge with previous patch).

From: Miquel van Smoorenburg <miquels@cistron.nl>
      Joe Thornber <thornber@redhat.com>

This implements the queue congestion callout for DM stacks.  To make
bdi_read/write_congested() return correct information.

- md->lock protects all fields in md _except_ md->map
- md->map_lock protects md->map
- Anyone who wants to read md->map should use dm_get_table() which
  increments the tables reference count.

This means the spin lock is now only held for the duration of a
reference count increment.

Udpate:

dm.c: protect md->map with a rw spin lock rather than the md->lock
semaphore.  Also ensure that everyone accesses md->map through
dm_get_table(), rather than directly.

From: Miquel van Smoorenburg <miquels@cistron.nl>

The VM and VFS use the address_space_backing_dev_info to track the realtime
status of the device which backs the mapping.  The read_congested and
write_congested fields are used to determine whether a read or write
against that device may block.

We use this infrastructure to

a) allow pdflush to service many queues in parallel (by not getting
   stuck on any particular one) and

b) to avoid undesirable and uncontrolled latencies in places such as
   page reclaim and

c) To avoid blocking in readahead operations

The current code only supports simple disk queues (and I have a patch here
for NFS).  Stacked queues (MD and DM) don't get this information right and
problems were expected.  Efficiency problems have now been noted and it's
time to fix it.

This patch lays down the infrastructure which permits the queue
implementation to get control when someone at a higher level is querying
the queue's congestion state.  So DM (for example) can run around and
examine all the queues which contribute to the higher-level queue.


It also adds bdi_rw_congested() for code in xfs and ext2 that calls both
bdi_read_congested() and bdi_write_congested() in a row, and it was "free"
anyway.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

The rewritten qeth network driver.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

The crypto device driver for PCICA & PCICC cards, part 2.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

The crypto device driver for PCICA & PCICC cards, part 1.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

zfcp host adapter log message cleanup part 2:
 - Shorten log output.
 - Increase log level for some messages.
 - Always print leading zeroes for wwpn and fcp-lun.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

zfcp host adapter log message cleanup part 1:
 - Shorten log output.
 - Increase log level for some messages.
 - Always print leading zeroes for wwpn and fcp-lun.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

zfcp host adapter fixes:
 - Reuse freed scsi_ids and scsi_luns for mappings.
 - Order list of ports/units by assigned scsi_id/scsi_lun.
 - Don't update max_id/max_lun in scsi_host anymore.
 - Get rid of all magics.
 - Add owner field to ccw_driver structure.
 - Avoid deadlock on bus->subsys.rwsem.
 - Use a macro for all scsi device sysfs attributes.
 - Change proc_name from "dummy" to "zfcp".
 - Don't wait for scsi_add_device to complete while holding a semaphore.
 - Cleanup include files in zfcp_aux.c & zfcp_def.h.
 - Get rid of zfcp_erp_fsf_req_handler.
 - Proper link up/down handling.
 - Avoid possible NULL pointer dereference in zfcp_erp_schedule_work.
 - Remove module_exit function. Without an external release function for
   the zfcp_port/zfcp_unit objects module unloading is racy.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

DCSS block device driver changes:
 - Fix remove_store function, put_device is called too early.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Network driver changes:
 - ctc: move kfree of driver structure after the last use of it.
 - netiucv: stay in state startwait if peer is down.
 - lcs: initialize ipm_list and unregister netdev only if it is present.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

dasd driver changes:
 - Fix check for device type in error recovery for fba devices.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Tape driver changes:
 - Add missing break in tape_34xx_work_handler to avoid misleading message.
 - Cleanup offline/remove code.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Common i/o layer changes:
 - Avoid de-registering a ccwgroup device multiple times.
 - Remove check for channel path objects in get_subchannel_by_schid.
   Channel patch objects are never in the bus list.
 - Avoid NULL pointer deref. in qdio_unmark_q.
 - Fix reference counting on subchannel objects.
 - Add shutdown function to terminate i/o and disable subchannels at reipl.
 - Remove all ccwgroup devices if the ccwgroup driver is unregistered.

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390 core changes:
 - Fix _raw_spin_trylock for 64 bit.
 - Add clarification to s390 debug debug documentation.

From: William Lee Irwin III <wli@holomorphy.com>

The following patch consolidates redundant code in various hugetlb
implementations.  I took the liberty of renaming a few things, since the
code was all moved anyway, and it has the benefit of helping to catch
missed conversions and/or consolidations.

From: Arjan van de Ven <arjanv@redhat.com>

patch below fixes a missing \n in a printk; without this you get to see a
<4> in the middle of that line...

From: <gerg@snapgear.com>

Add support for boards that have a 64MHz clock to common Coldfire header.

From: <gerg@snapgear.com>

Add type specifier to printk calls in 68EZ328/ucdimm setup code.  Patch
original from kernel janitors.

From: <gerg@snapgear.com>

Clean up debug trace in startup code of 68EZ328 DragonEngine board.

From: <gerg@snapgear.com>

A couple of fixes for the DragonEngine sepcific setup code:

. remove cs8900 ethernet setup from here
. add type specifier to printk calls (from kernel janitors)

From: <gerg@snapgear.com>

Some fixes for the 68360 common ints management code:

. use irqreturn_t for return type of interrupt handlers
. add type field to printk calls (from kernel janitors)
. there is no loop in show_interrupts(), don't use continue

From: <gerg@snapgear.com>

Some fixes for the 68328 common ints management code:

. use irqreturn_t for return type of interrupt handlers
. clean up asm code to be gcc-3.3.x clean
. add type field to printk calls (from kernel janitors)
. there is no loop in show_interrupts(), don't use continue

From: <gerg@snapgear.com>

A number of small fixes for the Motorola 68328 setup code:

. fix interrupt routine return types to be irqreturn_t
. add type specifier to printk calls (from kernel janitors)
. rework asm code to be gcc-3.3.x clean

From: <gerg@snapgear.com>

Fixes to the Motorola ColdFire 5407 setup code:

. fix interrupt routine return types to be irqreturn_t
. add DMA base addresses array
. support compile time setting of kernel boot arguments

From: <gerg@snapgear.com>

Add type specifier to printk calls.  Patch originally from kernel janitors.

From: <gerg@snapgear.com>

Add type specifier to printk calls.  Patch originally from kernel janitors.

From: <gerg@snapgear.com>

Add type specifier to printk calls.  Original patch from kernel janitors.

From: <gerg@snapgear.com>

Conditionaly copy an attached ROMfs filesystem in memory on kernel startup.
This should only be done if there really is a ROMfs there.

From: <gerg@snapgear.com>

Add type field to printk call.  Original patch supplied bu kernel janitors.

From: <gerg@snapgear.com>

Fixes to the Motorola ColdFire 5307 setup code:

. fix interrupt routine return types to be irqreturn_t
. add DMA base addresses array

From: <gerg@snapgear.com>

. add type field to printk calls (from kernel janitors)
. there is no loop in show_interrupts(), don't use continue

From: <gerg@snapgear.com>

Add start up code specific to the newly added COBRA5282 board.

From: <gerg@snapgear.com>

Fixes to the Motorola ColdFire 5282 setup code:

. fix interrupt routine return types to be irqreturn_t
. add DMA base addresses array

From: <gerg@snapgear.com>

Add startup code specific to newly supported COBRA5272 board.

From: <gerg@snapgear.com>

Allow for auto-detecting the size of the DRAM in the startup code for the
Motorola/5272 (ColdFire) board.  Use the DRAM sizing register, since it will
have been setup by the debug boot monitor (dBUG).

From: <gerg@snapgear.com>

Add type field to printk calls in m68knommu timers.c

From: <gerg@snapgear.com>

Define the DMA register set base address array for those m68knommu/ColdFire
CPU's that have a DMA engines.

From: <gerg@snapgear.com>

Add type field to printk calls in m68knommu mm/init.c.  Patch originally
from kernel janitors.